Protective system for punch presses or other machines



May 25, 1954 KQCH 2,679,307

PROTECTIVE SYSTEM FOR PUNCH PRESSES OR OTHER MACHINES Filed Aug. 22,1951 2 Sheets-Sheet 1 INVENTOR. fir'ai/a/r 0c// Arm/ms? May 25, 1954 K2,679,307

PROTECTIVE SYSTEM FOR PUNCH PRESSES OR OTHER MACHINES Filed Aug. 22,1951 2 Sheets-Sheet 2 INVENTOR. FQEOfR/CK /\.o 09

ATTORNEX Patented May 25, 1954 ATE-NT OFFICE B T cTIVE-sYs-IEM FoR-PuNoPnnss s oa'lornnn MACHINES Ereclcricl; Koch, Sparta Rutherford, v

Application August 22, 1951;"Serial-No.- 243,149

1 plaim. l

-Ihe invention herein disclosed relates. to the protection of punchpresses and. other machines against inaccuracies or failure in thefeedingof stock thereto.

Particularly .the. invention is concerned with presses equipped withmeans such as a slide. feed for automatically. supplying the machinewith stock.

Theigeneral purposeof the-invention is. to pro- -Such. reasons. might bethe buckling of the stock, between theieed unit. and the die, punch.orother; toolportion of the vpress, failure, to impart a fullfeedcstroketo the stock, reaching the end. of therstoclconthestock,beingtoo thick or too thin or. too Wide. or too, narrow.

. These and. other failures .or inaccuracies are guarded againstinthe-present invention byrthe provision of appropriately placeddetector switches allconnected-in such relation that the actionef any.one of themwill, serve to trip or stop=the press orothermachine.

1 Particularly it is. .an .iobject ;of the -invention .to provide such aprotective system in a simple,

practical form readily applicable to.. rna chines in use.

Other desirable'objects attained by the invention are set forth, orwill,appear in the course I :of thefollowing specification.

The drawings accompanying and forming part of the specification areillustrative of i present commercial embodiments of the-intention butstructureand arrangement may he modified and changed as-regards silchillustration, all within the true intent and scope of theinvention ashere nafter defined and claimed.

. Fig. 1 in the drawings is a side elevation of a power press havingtheinVentiOn applied thereto and showing the pressin normal runningcondition with the starting pedal held down byfthe automatictrip-mechanism;

2 is an interior view of the controlbox removed. from the pressandshowingthe parts as they appearin Fig. 1;

Fig. 3.is an end view of the control unit; Fig.- 4 is a horizontalsectional view on substantially the plane of--line 4 5 of Fig. 2;

Fig. 5 is a broken front elevation of the press showing two of thedetector switches the main control switch mounted thereon;

Fi 6 is Wirin diagra ,Eig. 7 isan-internal view of a -modifiedv-form .0?o r l; x;

Figs. 8, 9 and are hrokendetail-views/illus- .trating. operation of.this. second form of the in- 1 .vention;.. Fig. 8 :showing. position.of .parts. ,-wi th the machine locked in running .position;;..Fig.; 9

., showing .themachine tripped, with thesolenoid .deenergized. and.ethe. trip rod .moving upward; andFig. .10, showing. 1 the stoppedposition. with the trip rod upand lockedin thatrelation byreenergization; of the; solenoid;

. Fig. 11,.is a wiringidiagram .showing; par.ts ,,as in the locked,Fig.,10, position.

In Fig. l a power press isshownhaving.aioot pedal 'l,,,for;star ting and.controllingihesame.

- This may be considered agonesrevolutionpress ththcpu lrod 8 extendin-f m thepeda ,connected with arock lever. 9 having atripcon- ,ne t on mi8 ext ndin n ith one-revo utio clutch of the press.

Fu ther, it may-.be con i erc l.th th res 5. qu pp dwi a s i f e part xsowna I l n F 5. operatedir m thepre sand a ran to advanc st i tock. .scprs e t th ompanion. die memb n; ca r e b -.--.t.

; .lca ineit e pe l asap i .r I 5 and bolst 16! he, i ention. inclu s, mchan 1 lat i ea ld n the edal. dow science s oc is being properly fed,and-{fol automatically ree press if stock is not Pr per y. advancednr...sam [o h r d fe .1.9

.l ihelie l-xiown leic h wn. s when. cran ever. .l'i piyot ed at ISZinabox or case fl9 adapted to be ho ted atj Zilpvr the side of the .i rsen sc trr s aihei ri hit o the same. a projecting: lug 2 Z to engageover a stop block 3 ,e tab y-. 9 @n;.-.-ihe.; u re 8 set screws.

A- spring 25 acting on the horizontal arm 26 tends .to retract thehookjor nose end of thebell crank and a magnet 27 having. its armature-28 connected with this arm. acts to rock the detent outward into holdingengagement with the ,trip lOCl. A i

in series with thellatchingand trippingv magnet,

By arranging feeler switches Iontesting-different conditionsand byconnecting theseilall the znachinefmayibernadeto stop'when anyone or allof the conditionsguarded against occurs. 4 In the present illustrationthereIisf arunout switchill. positioned to detect the end. of the stock,a switch 3B .for',detectingbucklingofthe j stock .between the ieedudevice and. dies and; a

switch ,3: positione'dj toladetect j short feeding Lof the stock.

These may be microswitches, therunout switch by the stock and the buckleswitch normally closed and arranged to be pushed open by the upwardbuckling of the stock. Additionally, an on and ofi switch 32 may belocated in convenient position on the front of the press for renderingthe protective system operative or inoperative.

The various feeler switches may be connected in circuit when and ifrequired, by flexible electric cords 33 equipped with attachment plugs34, Fig. 1, adapted to be engaged in plug receptacles 35 on the front ofthe control box IS.

The wiring for these series connected receptacles while not shown indetail, is illustrated generally in the wiring diagram, Fig. 6, whichshows the three feeler or detector switches in use as connected inseries in the supply line 36 for the trip magnet 21.

Fig. 1 shows the supply line for the holding magnet as completed by anelectric cord 3'! equipped with an attachment plug 38 for engagementwith a plug receptacle in an ordinary wiring circuit.

In the case illustrated the control box is equipped with four plugoutlets 35. Only three of these are shown as in use. The circuit at thefourth outlet may be temporarily closed by a jumper or connection ofsome sort, such as a fuse plug. Instead of using jumpers for the plugoutlets not in service, these outlets may be of the normally closed orshort circuited design which will open up to connect an extension cordin circuit when the plug of such cord is inserted in the receptacle. Insuch a construction the circuit at the plug receptacles will be normallyclosed but an extension cord circuit may be connected at any time bysimply plugging it into one of the receptacle outlets.

The invention makes it possible to readily convert an ordinary punchpress with a stock feeding unit into an automatic production machinewhich will continue in operation unattended so long as the right stockis properly fed to the same, and which will automatically stop, with theram lifted, if stock is not present or is deiective or is improperlyfed.

The control box is a simple but substantial unit which can be bolted tothe side of the machine and in that relation provides a rugged andreliable means for holding the machine in operation and for tripping themachine and saving it from improper operation.

The microswitches may be mounted in position to detect variousirregularities or faults in feeding, by the use of suitable mountingclamps, brackets or the like such as shown at El, Figs. 1 and 5, andthey are connected in circuit by simply plugging them into openreceptacles on the control box.

Figs. 1, 2 and 6 show the stop block 23 as having a bevel or incline atthe'under side of the same, opposed to the hook portion 22 of the bellcrank to act as a cam to force the bell crank back, against the pull ofthe magnet, so that with the magnet energized, after setting up thepress, the foot pedal may be depressed to start the press.

The second form of the invention illustrated in Figs. '7 to 11, includesas an additional safety factor, means for locking the press in thestopped position and requiring purposeful, manual action on the part ofthe operator to again start the press.

Fig. 11 shows the holding latch in the form or" a sliding bolt 4|carried by a solenoid core 4 17.2 and arranged to be projected from thecontrol box 43 by solenoid winding 44 and to be retracted by fiat spring45.

The solenoid may be connected in the energizing circuit 35 in serieswith the several control units, as shown in Fig. 11, so that as in thefirst instance, it will be energized when all these switches are closedand will be deenergized when any one of them is opened.

Figs. 7 and 8 illustrate the normal running position of parts with thesolenoid energized and the bolt 4| projected over the top of the stopblock 23, holding the rod 8 down with the treadle of the press down inthe running position.

Fig. 9 illustrates a tripped, temporary condition of the parts in whichthe solenoid has been deenergized, the bolt 4| withdrawn by theretracting spring 45, releasing the stop block and permitting thetreadle rod 8 to move upward under impulse of the spring for yieldinglysupporting the treadle in the upper, stopped position of the press.

Fig. 10 shows the rod 8 all the way up, in the fully tripped positionand held in that relation by the slide bolt 4| projected in this case,beneath the holding shoulder of the stop block 23.

This projection of the bolt for securing the press in stopped conditionis automatically efiected in the illustration by a switch 46 located inthe control box, Fig. '7, which, as shown in the wiring diagram, Fig.11, is connected in a jumper circuit 43 bridging the several controlswitches and arranged to be closed by a plunger 42; positioned to beactuated by a trip block 49 in the upward movement of rod 8.

This trip block 49 is secured in position on the rod so that it willonly actuate the holding switch 46 after the block 23 on the rod haspassed up above bolt 4|, and will then retain plunger 48 in positionholding the switch closed.

Consequently in the form of invention shown in Fig. 7. the solenoid willbe automatically energized to secure and hold the press stopped any timeany one of the control switches has been actuated through any fault inthe feeding of the press.

To again start the press the solenoid is deenergized, in the caseillustrated, by a special release push-button 50 shown in wiringdiagram, Fig. 11, connected to interrupt the jumper circuit 41.

This arrangement requires that the operator of the machine take positiveaction to unlock the control mechanism before he can start the pressagain. In this case the switch button 50 must be pushed and held Whilethe foot pedal is being depressed to start the machine. If conditionsthen are in proper order the machine will start and continue to operate,but if any of the control switches are open the machine will again bestopped and be locked in the stopped relation.

In addition to control switches already mentioned, other controls may beprovided such as the guard indicated at 5! in Fig. 11 and which is inthe nature of a gate to swing down into position, closing access to thedies and which gate when swung down, closes a control switch 52connected in series with the other control switches.

This safety gate form of control may be plugged into the control box bya cord connection such as that indicated at 33 in Fig. 1'.

' In setting up this safety guard form of control the gate may beequipped with a point or projection such as shown at 53 in Fig. 11, toextend through an opening in the stationary structure in order tooperate the switch 52, to prevent accidental or unintentional closing ofthis switch.

Other forms of safety devices may be employed, the invention enablingthese to be quickly plugged into service relation on the control box.

The circuits shown in Figs. 6 and 11 are representative, it beingrealized that these may be modified and changed in various ways. Theymay include various forms of protective or safety devices such as fusesand the like, and condensers or resistors may be connected, as indicatedat 5 1, to prevent arcing and to otherwise take care of loads or surgesoccasioned by the control switches.

While normally closed circuits have been illustrated, it will beunderstood that the system may be designed for operation on a normallyopen circuit, with the control switches arranged in parallel, opencircuit relation.

In the two examples illustrated in Figs. 2 and '7, the holding bolts areprojected by magnets in the form of solenoids and retracted by springs.

This arrangement may be varied, for one instance, gravity be employed inplace of spring force for retracting the holding bolt.

What is claimed is:

A unitary attachment for converting a power press, or like stockhandling machine, having a control member which, when held depressed,will keep the machine in continuous operation and comprising a controlbox having means for mounting the same in fixed relation on the machineadjoining said control member, an abutment on said depressible controlmember, a latch in said control box projectible to engage over saidabutment to hold the control member in the machine-running position andretractable to release said abutment to permit the control member tostop the machine, said latch in the projected position being yieldableunder engagement by the abutment to permit the control member beingdepressed to start the machine when the latch is in the projectedrelation and whereby said latch will then hold the control member in thedepressed position when the machine is started by depressing the controlmember, an electromagnet in said box arranged to effect release of thelatch from holding engagement with the abutment on the control member,electric receptacle outlets on said control box, stock detectingswitches, brackets for mounting said switches in different positions onthe machine for detecting different stock feeding conditions, said stockdetecting switches having cord connections terminating in attachmentplugs insertable in the difierent receptacle outlets on the control boxand electrical connections within the control boX for connecting any oneor any number of said stock detecting switches plugged into one or moreof said outlets in controlling relation with said electromagnet, andwhereby said stock detecting switches may be set up on the machine todetect difierent faults in the feeding of stock, and the control membermay thereupon be depressed to start the machine and the unit will keepthe machine in operation so long as no stock feeding fault, which anyone of said switches will detect, occurs and whereby when any such faultarises the electromagnet will effect release of the latch from holdingengagement with the abutment to permit the released control member tostop the machine.

References Cited in the file of this patent UNITED STATES PATENTSFOREIGN PATENTS Country Date Germany May 9, 1941 Number Number

